Reason for concern: Yankees

Rob Carr, Getty Images

There is a fine line between old and experienced, and the Yankees are tiptoeing on it. Although shortstop Derek Jeter, 38, looks like he'll play until 2035, give or take a season, other aging stars -- Alex Rodriguez and Mark Teixeira, for instance -- seem to be fading some. Rodriguez, in particular, is in a precipitous decline, and a bad game or two to start this postseason could send him into another playoff spiral.

There is a fine line between old and experienced, and the Yankees are tiptoeing on it. Although shortstop Derek Jeter, 38, looks like he'll play until 2035, give or take a season, other aging stars -- Alex Rodriguez and Mark Teixeira, for instance -- seem to be fading some. Rodriguez, in particular, is in a precipitous decline, and a bad game or two to start this postseason could send him into another playoff spiral. (Rob Carr, Getty Images)

There is a fine line between old and experienced, and the Yankees are tiptoeing on it. Although shortstop Derek Jeter, 38, looks like he'll play until 2035, give or take a season, other aging stars -- Alex Rodriguez and Mark Teixeira, for instance -- seem to be fading some. Rodriguez, in particular, is in a precipitous decline, and a bad game or two to start this postseason could send him into another playoff spiral.